The main thing that makes Skorne difficult to defeat is his ability to shoot seeking skull projectiles. When a skull is flying toward you, do a quick, tight loop. The skull will continue for awhile in a straight line. By the time it turns around and gets back to you, it may have disappeared. Other than Skorne's skulls, he has no attacks. As soon as you 'trick' a skull, start blasting at him with your long range attack, or use potions, especially if you are a wizard.